Changes of acetylcholinesterase activity in different rat brain areas following intoxication with nerve agents: biochemical and histochemical study

Acetylcholinesterase activity in defined brain regions was determined using biochemical and histochemical methods 30 min after treating rats with sarin, soman or VX (0.5 x LD(50)). Enzyme inhibition was high in the pontomedullar area and frontal cortex, but was low in the basal ganglia. Histochemical and biochemical results correlated well. Determination of the activity in defined brain structures was a more sensitive parameter than determination in whole brain homogenate where the activity was a "mean" of the activities in different structures. The pontomedullar area controls respiration, so that the special sensitivity of acetylcholinesterase to inhibition by nerve agents in this area is important for understanding the mechanism of death caused by nerve agents. Thus, acetylcholinesterase activity is the main parameter investigated in studies searching for target sites following nerve agent poisoning.     

Synthesis and biological activity of lipocortin-5 N-terminus: An attempt to define some structural requirements for activity

Summary We have determined that the peptide lipocortin-5 N-terminus (LIPO-5NT) was able to inhibit rabbit platelet aggregation in a concentration- and time-dependent manner. In order to assess which residues in LIPO-5NT were essential for its activity, an Ala-scan was performed by sequentially substituting alanine for each of the first six residues. We demonstrate that replacement of Gln³ by alanine increases inhibition by about 20 times, while substitution of Leu⁵ gives an increase in activity of about 70 times.Abbreviations Boc tert-butyloxycarbonyl - DCC N,N-dicyclohexylcarbodiimide - DCU N,N-dicyclohexylurea - DMF dimethylformamide - EtOAc ethyl acetate - FAB-MS fast atom bombardment mass spectrometry - HOAc acetic acid - HOBt 1-hydroxybenzotriazole - LIPO-5NT lipocortin-5 N-terminus - MeOH methanol - NMM N-methylmorpholine - Pmc 2,2,5,7,8-pentamethylchroman-6-sulphonyl - PPP platelet-poor plasma - PRP platelet-rich plasma - RP-HPLC reversed-phase high-performance liquidchromatography - TLC thin-layer chromatography - WSCD 1-ethyl-3-[3-(N,N-dimethylamino)-propyl]carbodiimide - Z benzyloxycarbonyl. Symbols and abbreviations are in accordance with recommendations of the Joint Commission on Biochemical Nomenclature of the IUPAC-IUB [Biochem. J., 219 (1984) 345].     

Spontaneous activity, economy of activity, and resistance to diet-induced obesity in rats bred for high intrinsic aerobic capacity

Though obesity is common, some people remain resistant to weight gain even in an obesogenic environment. The propensity to remain lean may be partly associated with high endurance capacity along with high spontaneous physical activity and the energy expenditure of activity, called non-exercise activity thermogenesis (NEAT). Previous studies have shown that high-capacity running rats (HCR) are lean compared to low-capacity runners (LCR), which are susceptible to cardiovascular disease and metabolic syndrome. Here, we examine the effect of diet on spontaneous activity and NEAT, as well as potential mechanisms underlying these traits, in rats selectively bred for high or low intrinsic aerobic endurance capacity. Compared to LCR, HCR were resistant to the sizeable increases in body mass and fat mass induced by a high-fat diet; HCR also had lower levels of circulating leptin. HCR were consistently more active than LCR, and had lower fuel economy of activity, regardless of diet. Nonetheless, both HCR and LCR showed a similar decrease in daily activity levels after high-fat feeding, as well as decreases in hypothalamic orexin-A content. The HCR were more sensitive to the NEAT-activating effects of intra-paraventricular orexin-A compared to LCR, especially after high-fat feeding. Lastly, levels of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) in the skeletal muscle of HCR were consistently higher than LCR, and the high-fat diet decreased skeletal muscle PEPCK-C in both groups of rats. Differences in muscle PEPCK were not secondary to the differing amount of activity. This suggests the possibility that intrinsic differences in physical activity levels may originate at the level of the skeletal muscle, which could alter brain responsiveness to neuropeptides and other factors that regulate spontaneous daily activity and NEAT.